ICMCTF2007 Session B1-1: Sputtering Coatings and Technologies

Tuesday, April 24, 2007 1:30 PM in Room Golden West

Tuesday Afternoon

Start	Invited?	Item
1:30 PM	Invited	B1-1-1 Sputter Deposited Reactive Multilayer Foils and their Use as Novel Heat Sources for Joining Materials, Such as Sputter Targets to Backing Plates T.P. Weihs (Reactive NanoTechnologies and Johns Hopkins University) Multilayer foils that react exothermically are a new class of nanostructured materials that can be used to solder or braze components together. The multilayer foils, called NanoFoil, range in thickness from 20 to 200 microns and they contain hundreds of nanoscale layers that alternate between materials with large heats of mixing, such as Al and Ni. By inserting a free-standing NanoFoil between two solder (or braze) layers and two components, heat generated by the reaction of the foil melts the solder and consequently bonds the components. The joining process can be completed in less than one second, in air, and at room temperature. The use of NanoFoil as a local heat source eliminates the need for furnaces or hot plates, speeds soldering and brazing processes, and dramatically reduces the total heat that is needed. Thus, temperature-sensitive components and metals and ceramics can be joined without thermal damage, over small or large areas. This presentation will first describe the vacuum deposition of NanoFoil and how one can control the energy, ignition and reactivity of these foils. Next, the use of NanoFoil as a local heat source for joining will be presented, with a particular focus on the bonding of sputtering targets to backing plates. Predictions and measurements of heat transfer during the reactive joining process will be offered and the strength and uniformity of the resulting bonds will be identified. These true metallic bonds have less than 3% voiding and have enabled substantial increases in sputter rates compared to identical targets bonded with conventional methods, for both metallic and ceramic targets.
2:10 PM		B1-1-3 Effect of Substrate Orientation on Film Properties using AC Reactive Magnetron Sputtering S. Pulugurtha, D. Bhat, M.H. Gordon, J. Shultz, J. Lapairo (University of Arkansas) CrN coatings were prepared by magnetron sputtering with target-substrate orientations varying between 0° and 90° and N2 flow rates of 43, 40 and 30 sccm. The coatings were deposited on (111) Si wafers at a chamber pressure of 0.2 Pa for 1 hr. Initial results indicate that the target-substrate orientation to the incoming flux of ionized species has a strong influence on the microstructure, phase and preferred orientation of the crystallites in Cr-N coatings. The SEM studies of the film morphology showed a distinct change from coarser, less dense coating to smooth, dense and fine-grained morphology as a function of the changing orientation of the substrate, while the cross-sectional micrographs showed a columnar growth of the crystallites independent of substrate orientation. When the target-substrate angle was varied from 0° to 90°, the average roughness (Ra) decreased from 78 to 23 nm. We report on the details of the microstructural and chemical characterization of the films deposited in this study. * Currently Program Manager, SBIR/STTR, National Science Foundation, Arlington, VA.
2:30 PM		B1-1-4 Current-Voltage Characteristics of the Novel High-Power Density Magnetron D.G. Teer, A.A. Goruppa (Teer Coatings Ltd., United Kingdom) A novel magnetron with an industrial size 665 cm² sputter target and with high power density (up to 40 W/cm²) on it has been investigated in this work. Featuring strong magnetic field above the target it is capable of sputter regimes at high power but low voltage. The magnetron operation with aluminium, titanium and graphite targets was investigated at different pressures in the chamber. To study the phenomenon a number of current-voltage characteristics have been taken. They demonstrate large increase in current with little or no increase in voltage, indicating efficiency of electron confinement near the target and possibly self-sputtering at higher power densities. Emission spectra in visible and near ultraviolet were recorded to analyze effects of sputtering at various power levels on the targets. Measurements have been taken of the current to a biased substrate depending on power applied to the magnetron. They reveal a substantial increase of current to the substrate, pointing to much denser plasmas in the substrate vicinity in comparison with standard magnetrons. The demonstrated properties of the magnetron make it an extremely prospective tool for a high speed PVD processes.
2:50 PM		B1-1-5 Determining Substrate Temperature in PVD Processes by AC Inverted Cylindrical Magnetron Sputtering A.N. Cloud, M.H. Gordon, D. Bhat, A. Aryasomayajula (University of Arkansas) The substrate temperatures encountered during PVD are of great importance to the properties and phases of thin films, particularly crystalline alumina. An Isoflux ICM-10 Dual Target Inverted Cylindrical Magnetron Sputtering system is used to deposit alumina, chromium oxide, etc. for which an experimentally determined substrate temperature is desired. Constraints inherent to the Isoflux system prohibit the use of a thermocouple. Instead, an innovative technique is applied. A pressure vessel containing temperature-indicating liquid (supplied by Tempil, Inc.) is used to measure the temperature. These indicators change phase at their design temperature and are easily checked after use. Preliminary indications point to a temperature of 350 ± 50°C for our crystalline alumina depositions. On going efforts should reduce the uncertainty to ± 5°C. Theoretical heat transfer calculations support the experimental evidence. Also to be examined are the effects of substrate location and substrate bias.
3:10 PM		B1-1-6 Characterization of Niobium Oxide Films Deposited by High Target Utilization Sputter Sources R. Chow, A.D. Ellis, Jr. (Lawrence Livermore National Laboratory) Niobium oxide was sputter-deposited reactively using a rotary magnetron and a new high-density plasma source. Both sources are of interest because of high target utilization with an enlarged plasma beam footprint. The rotary magnetron in this study has a 125 mm diameter Nb metal target. From the reactive sputter hysteresis, the use of a plasma emission monitor is necessary for the deposition of stoichiometric niobia. Niobia films about 200 nm thick were deposited at oxygen flow rates that produced visibly absorbing to non-absorbing oxides. A description of the high-density source and sputter configuration has been reported previously.¹ A remotely generated plasma beam of high density is focused onto a 100 mm diameter target. Deposition parameters were established to produce non-absorbing niobium oxide for films of about 350 nm thick. The quality of the niobium oxide films were studied spectroscopically, ellipsometrically, and with XPS. Coating stress and density were determined. The dispersion curves from this work are compared to those reported in the literature of e-beam² and other magnetron³ deposited niobium oxide films. This work (UCRL-ABS-224417) was performed under the auspices of the U.S. Dept. of Energy by Univ. of CA, Lawrence Livermore National Laboratory under Contract W-7405-Eng-48. ¹R. Chow, M.A. Schmidt, A.W. Coombs, J. Anguita, M.J. Thwaites, Niobium Oxide Film Deposition Using a High-Density Plasma Source, SVC 49th Ann. Tech. Conf. Proc., Soc. of Vac. Coaters, 2006. ²O. Arnon, T.J. Chou, Wide band measurement of the refractive index of optical thin films during their deposition, Thin Solid Films, 91, 1982, pg 23-31. ³M.G. Krishna, A.K. Bhattacharya, Processing and size effects on the optical properties of sputtered oxide thin films, Materials Science and Engineering B, 86, 2001, pg 41-47.
3:30 PM		B1-1-7 High Rate Deposition of Sputtered Carbon Coatings S.K. Field, A.A. Goruppa, D.G. Teer (Teer Coatings Ltd., United Kingdom) Chromium doped carbon coatings produced by closed field unbalanced magnetron sputter ion plating have already demonstrated exceptional wear resistance combined with high load bearing capability^1,2. They have been adopted for use on a wide range of mechanical parts including some in harsh environments such as fuel injection components. The tribological properties of these coatings, and their electrically conducting nature offers further potential for exploitation, but in order to broaden the envelope of application as far as possible it may be necessary to reduce process times and costs further. In particular, the production of thin, high quality carbon films in short times, at very low cost, is of considerable interest for applications such as fuel cells. Faster deposition rates are needed to meet these requirements. Modifications³ to the design of magnetrons has allowed operation of the magnetrons at much higher power. This has enabled deposition rates to be increased by up to three times. There is also scope to increase rates further. Coatings have been produced at different deposition rates and the tribological properties and film characteristics compared to those for coatings produced with standard magnetrons. High quality coatings were produced at the faster deposition rates and specific wear rates below 5x 10^-17 m³/Nm obtained from pin on disc testing at 80N load (1 to 2 GPa). ¹Stallard, J., Mercs, D., Teer, D.G. , and Shipway, P.H., A Study of the Tribological Behaviour of Three Carbon-Based Coatings, Tested in Air, Water and Oil Environments at High Loads. J Surf. And Coat. Tech., 2004, 177-178: 545-551. ²Field, S.K., Jarratt, M., Teer, D.G.. Tribological Properties of Graphite-Like and Diamond Like Carbon Coatings. J. Trib. Int., 2004, 37 : 949-956. ³Goruppa, A.A., Teer, D.G.; Current and Voltage Characteristics of the Novel High Power Density Magnetron. ICMCTF 2007, to be published.
3:50 PM		B1-1-8 Fabrication and Characterization of the Ni-P-Based Multicomponet Coatings F.B. Wu (National United University, Taiwan); J.G. Duh (National Tsing Hua University, Taiwan) Nickel-Phophorus-based multicomponent coatings, including Ni-P-Al, Ni-P-Al-Cu, and Ni-P-Al-Cu-Zn, were fabricated by multi-gun sputtering technique with novel composite target design. The pure Al and electroplated Ni-P thick films on pure Cu and brass were employed as sputtering sources of Al, Ni, P, Cu, and Zn for specific coatings. Elemental distribution was demonstrated by field emission electron probe microanalysis (FEEPMA) line profiling and characteristic X-ray mapping. Homogeneous elemental distribution and uniform coating thickness were observed for various Ni-P-based multicomponent coatings. Through X-ray phase identification, all the coatings exhibited an amorphous/nanocrystalline feature in the as-deposited state. The microstructure of the annealed multicomponent Ni-P-based coatings transformed from amorphous to nanocrystallinization of Ni and precipitation of various intermetallic compounds, such as NixPy and NipAlq, leading to an evolution in surface characteristics and microhardness. The introduction of the alloying components into Ni-P to form the multicomponent coatings gave rise to the increase in thermal stability and surface hardness of the Ni-P-based coatings. The correlation between alloying elements, precipitation strengthening, and surface characteristics were intensively discussed. Keywords: Sputtering, Ni-P-based, multicomponent, thermal stability, precipitation strengthening.
4:10 PM		B1-1-9 Microstructure Evolution and Dielectric Peroperties of Ba_{0.7√sub 0.3}TiO₃ Parallel Plate Capacitor with Cr Interlayer C.-C. Ho, B.-S. Chiou (National Chiao-Tung University, Taiwan); L.-C. Chang (Huafan University, Taiwan) The microstructure, crystalline phase, surface morphology, and dielectric property of a novel sandwiched structure of Pt/BST/Cr/BST/Pt capacitor were characterized to understand the influence of the nano-Cr interlayer. BST dielectrics inserted with Cr film of thickness ranged from 2nm to 15nm all showed the crystalline cubic phase. However, a TiO₂ phase was formed on the upper BST layer after the BST/Cr/BST dielectrics were annealed at 800°C in O₂ atmosphere. In this study, cross-section TEM, SEM, X-ray diffraction, and EDS are employed to investigate the microstructure evolution of the BST/Cr/BST dielectric after annealing. The correlations between the microstructure and the dielectric property of the BST/Cr/BST capacitor with various thicknesses are explored.
4:30 PM		B1-1-10 Structure and Mechanical Properties of WC-DLC Multilayer Coatings B.R. Pujada, G.C.A.M Janssen (Delft University of Technology, Netherlands) Tungsten carbide-diamond like carbon (WC-DLC) coatings deposited by reactive magnetron sputtering from WC target in an argon-hydrocarbon plasma, are gaining considerable scientific and industrial interest. Thanks to their low friction coefficient and high wear resistance in comparison to conventional coatings, these are used as protective coatings for a wide range of applications. Multilayered hard coatings composed of two alternating layers are of great interest because the presence of a high number of interfaces. In this work, the structure and mechanical properties of WC-DLC multilayered coatings are studied. WC-DLC multilayer coatings have been deposited by RF magnetron sputtering form a WC target and periodic switching on and off of the reactive acetylene gas flow. The period of the acetylene gas flow modulation was varied between 8 sec. and 20 min. and the total deposition time was kept at 2 h. Microstructure and mechanical properties have been studied by cross-sectional transmission and scanning electron microscopy, X-ray diffraction, nanoindentation and substrate curvature. It has been observed that the hardness decreases from 21 GPa to 17 GPa when the bilayer thickness is reduced from 100 nm to 5 nm. Also, by varying the thickness of the multilayers the compressive stress can be varied from 2.5 GPa to 1.6 GPa. Our results show a minimum compressive stress of "0.8 GPa for bilayer thickness of around 5 nm. These observations are discussed in terms of individual properties of each layer, the interface stress and mixing between layers.